Clamping apparatus

ABSTRACT

A sheet clamp means clamps the vertical edge of a bathtub shower curtain adjacent a wall to provide an effective seal. The clamp means includes a camming means which applies forces to rotate pins carrying a swinging clamp plate. Both gravity-actuated and force-actuated sheet clamps are shown.

United States Patent Laauser Sept. 5, 1972 [54] CLAMPING APPARATUS 3,205,547 9/1965 Riekse ..24/243 N [72] Inventor: Richard P. Laauser 48 Mead St. 3,365,684 1/1968 Stemke et a1. ..4/149 X Walton, 13856 FOREIGN PATENTS OR APPLICATIONS Filedi p 1971 964,601 5/1957 Germany ..24/67 R [21] APPL No: 1 0 972 66,500 9/1914 Austria ..24/67 R Related U.S. Application Data Primary Examiner-Donald A. Griffin [62] Division of Ser. No. 63,522, Aug. 13, 1970, Stephens Pat. No. 3,631,543. [57] ABSTRAUI,

[52] U.S. Cl ..24/263 PJ, 4/149 A'sheet clamp means clamps the vertical edge of a [51] Int. Cl. ..A47k 3/14, A47k 3/16 bathtub shower curtain adjacent a wall to provide an [58] Field of Search ..4/ 149, 153-155; effective seal. The clamp means includes a camming 24/67 R, 263 PJ, 263 PC, 263 R, 243 K, 243 means which applies forces to rotate pins carrying a M, 243 N swinging clamp plate. Both gravity-actuated and forceactuated sheet clamps are shown. f ted [56] Re erences Cl 5 Cl 13 Dm Figures UNITED STATES PATENTS 2,131,156 9/1938 Yardley ..4/149 sum 1 of 4 FIG.

PATENTEDsEP 5 m2 PATENIEUsEP 51912 SHEET 3 [IF 4 FIG.5

CLAMPING APPARATUS This application is a division of my prior copending application Ser. No. 63,522 filed Aug. 13, 1970 and now US. Pat. No. 3,631,543 issued Jan. 4, 1972.

My invention relates to closure and sheet clamp devices, and more particularly, to an improved arrangement for closing shower curtains used with bathtubs or shower stalls. Bathtubs equipped with shower fixtures are commonly equipped with plastic or cloth shower curtains slidably suspended on a curtain rod which extends the length of the tub, and which is mounted 4 or 5 feet above the outer edge of the tub. Three vertical sides of a shower enclosure are ordinarily formed by three walls extending upwardly from three sides of the tub, and the shower curtain, when closed, forms a fourth wall. In order to prevent water from splashing onto the floor outside the tub off of an occupant of the tub, or off of walls partially surrounding the tub, it is necessary that the vertical edges of the shower curtain lie closely adjacent the walls at the ends of the tub, without gaps through which water may splash. Whether water tends to splash out past one end or the other end of the shower curtain, or past both ends, tends to depend upon the angle at which the shower head is adjusted. Changing the angle decreases leakage adjacent one end of the tub but increases leakage at the other end of the tub. In installations where rather long tubs are provided, the shower head can be directed to spray in a direction having a substantial horizontal component and an occupant can stand sufficiently far away from the shower fixture, sometimes little tends to splash out at the end of the tub where the shower nozzle is located, but mostly at the other end of the tub. In installations using shorter tubs, so that the nozzle stream must be directed more downwardly and the occupant must stand nearer the nozzle, it is usually necessary that both vertical edges of the curtain lie snugly against their respective end walls if deflection of water onto the outside floor is to be avoided. For decorative purposes many homeowners employ two shower curtains suspended from the curtain rod, including an inner shower curtain ordinarily made of water-proof plastic or rubber sheet and adapted to hang with its lower edge inside the tub, and an outer curtain frequently comprising a printed cloth fabric which is intended to hang with its lower edge outside the tub. Loops or the like which attach the upper edge of the inner curtain to the curtain rod are ordinarily spaced in staggered relation between loops holding the upper edge of the outer curtain, so that the two curtains open and close together.

Both cloth and plastic shower curtains are necessarily made very flexible so that they may be slid easily to one end or the other of the curtain rod to allow entry into and egress from the tub. The flexibility of such curtains tends to allow their edges to be moved away from the walls by air currents and water streams within the shower enclosure and sometimes by various movements of a person within the tub, so that water frequently is splashed on the floor adjacent the tub. Some plastic curtains tend to acquire some set when bunched at one end of the curtain rod, and that set also makes it difficult to position a curtain so as to avoid leakage onto the floor. Water on the floor adjacent the tub not only may provide a serious safety hazard, but it also may damage sub-flooring and the like. Similar tub. The magnets are used on the inner curtain, of course, if an outer decorative curtain is used. The lower edge of the curtain containing the magnets must hang inside the tub to prevent leakage of water onto the floor outside the tub. At least one of the inside walls of bathroom tubs ordinarily slopes inwardly as well as downwardly in order to provide a comfortable sloping surface for tub bathing. The inward slope prevents one from locating a magnet on the bottom edge of the curtain directly below the end of the curtain rod to hold the vertical edge of the curtain taut and straight down, and hence, it is sometimes impossible to place the magnets so that open gaps between the curtain and the walls do not exist. Magnets are also disadvantageous in that movement of a magnet, whether due to air turbulence or movements of the person within the tub, results in the magnet then tending to hold the curtain partially open. Furthermore, some tub-installations such as those formed from fiberglass, are non-magnetic, as are most stall showers, so that magnets may not be used.

The serious deficiencies of magnetic curtain-closing arrangements are in some respects overcome by the use of sliding plastic or glass rigid doors in lieu of a shower curtain. Such arrangements commonly include a pair of doors which slide in pairs of adjacent tracks, one pair of tracks being mounted overhead, and another pair being mounted lengthwise along the tub atop the flat rim or ledge of the tub. While such arrangements effectively overcome the leakage problem associated with magnet held curtains, they have several other marked disadvantages. For example, no matter how the doors are slid, only one-half of the length of the tub can be open at any time. Such a limitation is very disadvantageous when one attempts to bathe an infant in the tub if the infant slides to the portion of the tub blocked by the pair of doors. The pair of sliding door tracks extending along the rim of the tub are also extremely uncomfortable to sit upon, or for one to rest on while leaning over the edge of the tub to bathe an infant. The tracks are also very difficult to keep clean, and indeed if they are kept perfectly clear and free from grease and the like, the sliding doors sometimes tend to stick. Another common type of tub-shower door arrangement includes a pair of folding doors, one of which is hinged at one end of a pair of upper and lower tracks, and the other of which slides along the tracks as the doors are opened and closed. The doors may be folded in their wide open position so that they lie adjacent the wall opposite the shower fixture. While this arrangement allows substantially the entire length of the tub to be open when desired, it also has the mentioned disadvantages of the tracks. It is further disadvantageous in that one must get inside the tub and close the folding doors in order to clean the wall against which the doors fold, and in that one cannot conveniently mount a towel bar on that wall. A number of persons dislike shower doors, due to a fear, perhaps unjustified in most instances, of being cut by broken .glass or plastic doors. The tracks associated with shower doors can appreciably increase the probability of lacerations due to falls in or near a bathtub. The cost of shower door installations on a bathtub is also far greater than that of a shower curtain, and the proper installation of shower doors ordinarily requires a fairly skilled mechanic. The weight of shower doors requires that they be fastened to wall studding or the like, using heavy lag screws, so that holes must be drilled through wall tile. The holes are unsightly if door trim is later removed.

A primary object of the present invention is to provide an improved shower curtain closing arrangement which overcomes the mentioned disadvantages of prior curtain arrangements, and which does not have any of the disadvantages of the mentioned shower door arrangements. It will become apparent, moreover, as the description proceeds, that the present invention provides a sheet clamping means having wide utility in many applications other than shower curtain applications, and a broad object of the present invention is to provide an improved sheet clamping means which will securely hold the edge of a sheet, without any need for grommets or fasteners of any type to be provided in the edge of the sheet. Other objects of the invention will in part be obvious and will, in part, appear hereinafter.

A central concept of the present invention as applied to a tub shower curtain clamping application involves the provision of an elongated vertically extending clamping means mounted against the wall at one end of the tub and extending upwardly from the rim of the tub, the clamping means being adapted to grip a vertical edge of the shower curtain along a substantial portion of its length, and thereby maintain an effective curtain position which prevents water from being splashed outside the shower enclosure formed by the tub, the three surrounding walls and the shower curtain. To be readily usable by persons of all ages and simply operated to effectively clamp a curtain edge without tedious curtain adjustments, the clamp is gravity-operated, so that it will hold the edge of the curtain with a predetermined desired force. The clamp is arranged to grip the curtain with the predetermined force no matter how far the clamp is closed, within wide limits, so that the clamp will grip the curtain with the predetermined force even if the edge of the curtain is somewhat wrinkled, and irrespective of the thickness of the curtain edge. Furthermore, the clamp is operable very simply between open and closed positions, it will automatically latch in a wide-open position, and it will automatically close without adjustment to whatever closed position is made necessary by the thickness of the curtain edge. In some installations a clamping means will be provided at only one end of a tub, while in other installations a pair of clamping means will be used, one at each end of the tub. While the invention will be described in connection with a tub shower, it will become apparent that the invention is readily applicable to use with a shower curtain which extends across a conventional shower stall.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

FIG. 1 is an elevation view of a conventional tubshower arrangement with one form of the invention installed, except that the shower curtain used with the arrangement has been omitted for sake of clarity.

FIG. la is a plan view taken at lines la-1a in FIG. 1.

FIG. 2a is a view taken at lines 2a-2a in FIG. 1 and enlarged, except that the improved clamp of the invention is shown in closed position in FIG. 1 and in an open position in FIG. 2a.

FIGS. 2b through 2e are section views taken as indicated by similarly designated section lines in FIGS. 20 and 2c.

FIG. 3a is a view similar to FIG. 2a but with the clamp shown in a partially closed condition.

FIG. 4 is a geometrical diagram useful in understanding the operation of the invention.

FIG. 5 is a side view of a portion of a modified form of the invention, and FIG. 5a is a view taken at lines 5a5a in FIG. 5.

FIG. 6 is a top view of a further modified form of the invention.

In FIG. 1 a typical modern tub shower installation includes a tub 10 mounted between end walls 11 and 12 and against side wall 13. The three walls ll13 commonly comprise lath and plaster and ceramic tile carried on vertically extending studding members such as 14 and 15. Wall 11 is shown equipped with an adjustable shower head 16, a mixing valve control 17, and hot and cold water control valves 18 and 19, only one of which is visible in FIG. 1. Tub 10, which is commonly formed of porcelainized cast iron or sheet steel, is provided with a conventional faucet 21 and a drain 22. The plumbing connections, which are not shown, all may be assumed to be conventional, and they form no part of the present invention. A conventional recessed soap dish 23 is shown mounted in back wall 13. A conventional shower curtain rod 24 extends between end walls 11 and 12 at a location above the outer rim 10a (FIG. 1a) of tub 10. The inside of tub 10 at one end slopes leftwardly as well as downwardly, as shown at 10b, to provide a comfortable surface against which one can rest ones back while taking a bath.

If a conventional shower curtain (not shown) carrying magnets along its lower edge is slidingly suspended from rod 24, the magnets may be made to adhere to the inside of the outer wall of tub 10, typically at spaced points along a line such as line 26 in FIG. 1. Because of the inward slope of the tub as at 10b, the rightmost magnet on the curtain must adhere to tub 10 no further to the right than at point 104:. If a magnet at the corner of the curtain grips tub 10 at point 10c, the edge of the curtain will extend approximately along line 27 or line 28 in FIG. 1, which depending upon the ease with which the curtain hooks or rings slide along rod 24, and depending upon the tension in the curtain which in turn is dependent upon the vertical level at which the magnet is made to adhere to the tub. In either case, it will i be seen that a gap or opening will exist between wall 12 and the edge of the curtain which will allow water to be splashed out of the tub onto the bathroom floor 30. A similar gap or opening will occur at the other end of the tub adjacent wall 11, although that gap will tend to be less, if the tub wall is less thick and more vertical, as shown in FIG. 1, so that the distance between points f and 10g is less than that between points 100 and Md. The front and rear rims of most existing tubs have substantial width, so that appreciable gaps occur at both vertical edges of a shower curtain held in place by magnets. The gap between the right vertical edge of the curtain and wall 12 may be lessened somewhat if the curtain width is made substantially greater than the length of the tub, so that a portion of the curtain can fold around the comer of the tub and extend for some distance toward back wall 13. Such an arrangement is disadvantageous because longer curtains are most costly, more curtain hooks or rings are required, and the curtain cannot be completely spread out so that it will dry in a substantially flat condition without wrinkles. Furthermore, even though the bottom corner of the curtain then can be located some distance toward wall 13, the top corner of the curtain is restrained by rod 24, so that a gap through which water may pass will continue to exist.

In accordance with the present invention, a vertically extending clamp means generally indicated at 32 is mounted against wall 12 atop the rim of tub 10 at the outer corner of the tub. The clamp means, which is described in detail hereinbelow, includes a handle 33 which the occupant of the tub may actuate to clamp a substantial length of the right vertical edge of the curtain so that gap or openings through which water may pass are eliminated.

As best seen in FIGS. 2a-2e, the curtain clamp means shown therein in a wide open position includes a base plate portion 35 fixedly mounted at the outer comer of tub 10 atop the flat rim 10a of the tub. Plate 35 preferably is provided with a flat bottom surface, and with a slightly varying thickness in two dimensions. More specifically, the top surface of plate 35 is preferably arranged to slope slightly downwardly to lesser thickness (in the directions indicated by arrows 36 and 37 in FIG. 2b, so that any water which drips on plate 35 tends to run back into the tub, and toward end wall 12. The bottom of plate 35 is fastened atop rim 10a of the tub, preferably by use of a mastic adhesive. Extending upwardly from base plate 35 is a generally L- shaped or angle member 39 which is fixedly fastened to end wall 12, preferably also by use of a mastic cement, although lag screws and the like may be used. Because of the very modest weight of the clamping means of the invention, it may be adequately held in place with a mere adhesive mastic, so that no lag screws are required and no holes need be drilled through the wall tile. Member 39 extends upwardly to a short distance below the level of curtain rod 24, as shown in FIG. 1. Clamp plate 40 is swingably mounted to pivot and move relative to fixed member 39 in a manner to be described in detail, handle 33 being attached to clamp plate 40 to allow the occupant to conveniently lift and lower as well as pivot, the clamp plate.

As shown in FIG. 2a, clamp plate 40 is attached to fixed member 39 by two pivot pins 41 and 42. Pins 41 and 42 are each fixedly anchored to clamp plate 40, and each extends through a respective slot in member 39, lower pin 41 extending through lower slot 43 in fixed member 39, and upper pin 42 extending through upper slot 44 in fixed member 39. Pins 41 and 42 are provided with enlarged ends, preferably ball-shaped as shown, to retain them in slots 43 and 44. An enlarged recess is provided in member 39 behind each of slots 43 and 44 to accommodate the enlarged ends of pins 41 and 42, the recess 48 behind lower slot or track 43 being indicated in FIGS. 20, 2c and 2d. Recess 48 is made sufficiently larger than the ball end of pin 41 to allow the ball end to slide freely within the recess without binding.

Tracks or slots 43 and 44 through member 39 each will be seen to include a short substantially horizontal portion and a longer downwardly sloping portion which extends in a direction outwardly from the tub as well as downwardly. When clamp plate 40 is wide open, as shown in FIG. 2a, the shanks of pins 41 and 42 extend across and rest upon the substantially horizontal upper portions of slots 43 and 44, so that there is no tendency for clamp plate 40 to close. Fixed member 39 is preferably provided with a widened edge as shown at 39a in FIGS. 2b and 2c, and clamp plate 40 with a widened edge as shown at 40a in FIGS. 2a and 2c. When clamp plate 40 is pivoted toward a clamping position it pivots about a moving axis determined by tracks 43, 44 and pins 41, 42, and edge 40a of clamp plate 40 swings toward edge 39a of fixed member 39, allowing the vertical edge of a shower curtain to be securely clamped between members 39 and 40.

As the occupant of the tub begins to close the clamp, he pulls the handle upwardly, i.e. up perpendicular to the plane of FIG. 2, thereby unseating the shanks of pins 41 and 42 from the horizontal portions of tracks 43 and 44. The weight of clamp plate 40 thereby causes the clamp plate to descend, with the shanks of pins 41 and 42 riding downwardly, and rightwardly as viewed in FIG. 2a, along tracks or slots 43 and 44. Cam pad portions 43a and 44a situated adjacent slots 43 and 44, respectively, also act on pins 41 and 42 together with portions of slots 43 and 44 so as to rotate plate 40 about a vertical axis which simultaneously moves rightwardly (in FIG. 20) as pins 42and 43 slide down tracks 43 and 44. It should be noted that edge 43b of slot 43 is provided with a difi'erent slope from edge 430 of cam 43a.

The principle of operation of each cam and slot may be better understood by reference to the diagram of FIG. 4. It will be understood from FIGS. 2a and 20 that slot 43 engages pin 41 adjacent the enlarged head of the pin, while cam pad 43a engages pin 41 further from the head end of the pin. In FIG. 4 line 51 represents edge 43b of slot 43 that successively engages pin 41 as the pin slides down the slot, and line 52 represents edge 43c of cam pad 43a which successively engages pin 41 as the pin slides down the slot. The pin 41 is shown at five successive vertical positions and five corresponding angular positions. As the pin is forced down slot 43 by the weight of clamp plate 40, it will be clear that the varying distance between lines 51 and 52 will cause the pin to be rotated. If the two edges which engage a pin are straight as shown, it will be appreciated that the relationship between vertical translation and rotation of movable clamp plate 40 will be linear. It is within the scope of the invention, however, to curve one or both of the two edges, so that the rotation per amount of vertical translation varies as the clamp plate closes.

Though shown as lines in FIG. 4, the edge 43b of slot 43 which engages pin 41 and surface 43c of cam pad portion 43a actually are provided with appreciable width, so that they each make line contact (rather than the mere point contact) with pin 41 as the pin moves down the slot. Pin 42, slot 44, and cam 44a operate in the same fashion, of course, as pin 42, slot 43, and cam 43a. Also, it will be apparent that further similar pinslot-cam connections may be made between fixed member 39 and clamp plate 40, if desired. It will be apparent that the amount of pin rotation (and hence clamp plate 46 rotation) per amount of vertical movement may be selected easily by selection of the difference in slope between edge 43b and edge 430. Furthermore, as will be apparent from FIG. 4, the pins (and hence clamp plate 40) may be arranged to rotate more (or less) than 90 as they descend in their respective slots. A substantial difference in slope between edges 43b and 430 results in considerable rotation of clamp plate 46 for a small amount of vertical displacement of clamp plate 40, which is desirable in that the clamp plate pulls down only very slightly on the curtain as it clamps the curtain. The very slight pulling down on the edge of the curtain is advantageous in that it tends to maintain the edge taut and straight, but because the downward pull is very slight, no appreciable wear of the curtain results.

In order to clamp the shower curtain, the occupant of the tub pulls the curtain rightwardly as viewed in FIG. ll (leftwardly as viewed by the occupant within the tub) until one comer lies adjacent wall 12. With one hand the occupant may grasp the curtain edge slightly above the level of plate 35, pulling the curtain edgeslightly downwardly to make the edge slightly taut, so that the edge runs down a portion of fixed member 39 and covers edge 39a (FIGS. 2b, 2c). One can press a portion of the curtain edge down onto plate 35 in order to do so. Then one merely need dislodge clamp plate 40 from the wide open position shown in FIG. 2a with ones other hand. The clamp plate then will automatically descend and rotate in the manner described above, thereby clamping the curtain edge along the entire length of clamp plate 40. In order to release the curtain one need merely lift clamp plate 40 by means of handle 33, the clamp plate rotating to an open position, of course, as it is lifted.

In some installations it will be deemed satisfactory to provide the curtain clamp at only one vertical edge of the curtain, while clamps at both edges will be desired in some other installations. It will be apparent at this point without detailed explanation that clamps of the type shown may be in right and left-hand pairs to be installed adjacent opposite ends of the curtain rod. The shower curtain clamp device shown may be made entirely of metal, such as aluminum or steel, but I prefer for most applications that it be made of various plastics, by injection molding, for example. Cam pads 43a, 44a are preferably molded integrally with member 39. While various portions of the clamping means have been shown with sharp edges and corners for convenience in drafting, it will be apparent that such edges and corners may be rounded to insure that persons will not be cut or scratched. The very bottom of slot 48 (FIG. 2a) and other similar slots is preferably slanted slightly so that any water which enters those slots will drain from the slots, run down member 39, across plate 35, and into the tub. Pins such as 41 and 42 may be made separately from plate 40 and then screwed into or cemented in holes in plate 40. Alternatively, however, it is possible to mold pins 41 and 42 integrally with plate 40 and then snap their enlarged heads into place within slots such as 48 by temporarily deforming member 48 at the upper portions of slots 43 and 44, if member 39 is made from a sufficiently resilient plastic material.

FIG. 6 diagrammatically illustrates a top view of a modified form of the invention comprising a reversal of the previous embodiment in that the pin 41' carrying the ball-shaped end (not shown) is fixedly mounted on the stationary member 39, and the-camming slot (not shown) is provided in the movable clamping plate 40'. Clamping plate 40 is shown in a wide-open position in FIG. 6. As the plate is closed to clamp a curtain edge, the camming slot in plate 40' rides downwardly on pin 4 and the slot is shaped to cause plate 40' to rotate in the same manner as plate 40 of the preferred embodiment. Because the operation is directly inverse to that of the preferred embodiment, further explanation of FIG. 6 is deemed unnecessary.

While the preferred embodiment of the invention described in connection with a shower installation utilizes the weight of the pivoting clamp piece to automatically rotate the clamp piece as the clamp is closed, the clamping means of the present invention may be used in a variety of applications, such as horizontal applications, where other means are utilized to close the clamp. FIG. 5 illustrates a portion of a modified form of clamping means which may be used in either horizontal or vertical applications. Reference numerals corresponding to similar parts of FIG. 3a are shown, and movable clamp piece 40 is shown in a partially closed position similar to the position shown in FIG. 3a. As clamp piece 40 is moved downwardly in FIG. 5 to close the clamp, camming slots (not shown in FIG. 5) in fixed member 39 similar to those in FIG. 3a move piece 40 leftwardly relative to fixed member 39. When the clamp is less than fully closed, shaft 55 extending from piece 40 enters slot 56 in block 57 fixed to member 39. The tightening of wing nut 58 then urges washer 59 against face 57a of block 57, exerting a leftward pull on piece 40 relative to member 39. Face 57a is preferably canted as shown so that friction between the wing nut and block 57 do not prevent further motion of shaft 55 down into slot 56. The leftward force, which acts in the same manner as gravity does in FIG. 3a, but with much greater force, allows the clamp to be closed very tightly. The clamp of FIG. 5 has the advantage over various prior clamps in that the clamping force between the movable and fixed pieces 39 and 40 may be made very uniform along the whole length of members 39 and 40 even though the force is applied only at one end of the assembly, since the clamping force depends solely on the angle provided between the two edges of each cammin g slot. If desired, for some special application, the angle between the working edges of the various camming slots can be made to differ, so that a sheet would be clamped with different amounts of force at different points along its edge, and, if desired, cam pads corresponding in principle to 430, 44a in FIG. 20 could be made adjustable in position on piece 39 so as to allow various patterns of variation in clamping force. While a bolt-nut device is shown provided as a means to provide translation of piece 40 relative fixed member 39, a variety of different force producing means may be used in different applications of the invention, such as springs or levers, for example. Whether mounted vertically or horizontally, the sheet clamp of the present invention may be used to clamp the edges of a wide variety of sheetlike devices, including rigid or semi-rigid sheets as well as flexible sheets. For example, the device of FIG. may be used to clamp the edge of a canvas canopy which extends generally horizontally over a trailer, or to clamp the lower edge of a triangular sailboat sail to a boom, or to clamp any sheet-like device without any requirement for grommets or the like. In applications where great clamping forces are required, it will be apparent that metal construction will be required in lieu of plastic.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A sheet-clamping assembly for clamping the edge of a sheet which extends in a first direction, comprising, in combination: a first elongated member having a first clamping surface extending in said first direction; a second elongated member having a second clamping surface extending in said first direction; a plurality of pivot connections between said first and second members to allow relative pivotal movement between said members and thereby to allow relative movement between said first and second clamping members to grip said edge of said sheet between said first and second clamping surfaces, at least one of said pivot connections comprising means responsive to translation of one of said members relative to the other of said members in said first direction for pivoting said members relative to each other.

2. An assembly according to claim 1 in which said one of said pivot connections comprises a pin means having one end rigidly affixed to said first elongated member and slot means provided in said second elongated member, said slot means extending at an acute angle to said first direction and being adapted to retain the otherend of said pin means.

3. An assembly according to claim 2 in which said slot means includes a pair of edges adapted to engage said pin means at different distances from said other end of said pin means, said pair of edges extending at mutually differently varying acute angles to said first direction, whereby translation of said pin means along said slot means causes rotation of said means about a succession of axes parallel to said first direction.

4. An assembly according to claim 1 wherein said first direction is substantially vertical and one of said members is fixed stationary, whereby gravity causes vertical translation of said one of said members relative to said other of said members.

5. An assembly according to claim 1 wherein said first direction is substantially horizontal and said assembly includes means acting between said first and second members for causing translation of said one of said members relative to said other of said members. 

1. A sheet-clamping assembly for clamping the edge of a sheet which extends in a first direction, comprising, in combination: a first elongated member having a first clamping surface extending in said first direction; a second elongated member having a second clamping surface extending in said first direction; a plurality of pivot connections between said first and second members to allow relative pivotal movement between said members and thereby to allow relative movement between said first and second clamping members to grip said edge of said sheet between said first and second clamping surfaces, at least one of said pivot connections comprising means responsive to translation of one of said members relative to the other of said members in said first direction for pivoting said members relative to each other.
 2. An assembly according to claim 1 in which said one of said pivot connections comprises a pin means having one end rigidly affixed to said first elongated member and slot means provided in said second elongated member, said slot means extending at an acute angle to said first direction and being adapted to retain the other end of said pin means.
 3. An assembly according to claim 2 in which said slot means includes a pair of edges adapted to engage said pin means at different distances from said other end of said pin means, said pair of edges extending at mutually differently varying acute angles to said first direction, whereby translation of said pin means along said slot means causes rotation of said means about a succession of axes parallEl to said first direction.
 4. An assembly according to claim 1 wherein said first direction is substantially vertical and one of said members is fixed stationary, whereby gravity causes vertical translation of said one of said members relative to said other of said members.
 5. An assembly according to claim 1 wherein said first direction is substantially horizontal and said assembly includes means acting between said first and second members for causing translation of said one of said members relative to said other of said members. 